Arc welding



Oct. 26 1926. 1,604,181

J. F. LINCOLN ARC WELDING Filed Feb. 25, 1923 i Z J- i Z i M 3 WELDING c/Rczu-r' iy a j flf 127.7

INVLNTOR. $22265 fT'ZZinco/zz Patented Oct. 26, 1926.

UNITED STATES PATENT OFFICE.

JAMES F. LINCOLN, OF EAST CLEVELAND, OHIO, ASSIGNOR TO THE LINCOLN ELECTRIC COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

ABC WELDING.

Application filed February 23, 1923. Serial No. 620,746.

The difficulties involved in welding together light gauge metal sheets, particularl in the form of a continuous seam, are wel recognized. The so-called spot welding process has avoided these difliculties to a certain degree, but obviously this form of juncture is not satisfactory where a tight closure is required between the parts, as, for example, in a sheet'metal barrel or like container.

Various methods of lap welding, in which the necessary heat is developed by theresistance ofthe joint to the passage of current thereacross, have been devised, but without proving wholly successful under the conditions stated. The object of the present invention accordingly is the provision of an arc welding process whereby a continuous butt weldmay be formed between the meeting edges of sheets of relatively light gauge,

although of course the process is not. necessarily limited to working with such light gauge materials.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the steps hereinafter fully described and particularly pointed out in the claims, the annexed drawing and the following description setting forth in detail one mode of carrying out the invention, such disclosed mode consisting however, but one of various ways in which the principle of the invention may be used. Certain novel features are also involved in the apparatus and system of control herein disclosed and these form the 86 subject matter of my co-pending application filed April 4, 1921, Serial No. 458,268. out of which the present case has been required to be divided.

In said annexed drawing 50 Fig. 1 is a perspectiveviewmore or less diagrammatic in character. llustrating my improved method of welding; Fig. 2 is a cross-sectional detail: Fig. 2 is a similar view showing the resultant joint; Fig. 3 is a diagrammatic view of a typical apparatus and generalwiring scheme therefor; Fig; 4 is a wiring diagram showing system of con; trol employed in connection with the two motors that respectively advance the welding electrode along the work, and position the same with respect to such work; and

Figs. 5. 6 and 7 are detailed views similar to- Fig. 2 but showing modifications. The distinguishing features of my present 1 improved process are perhaps best illustrated in Fig. 1, wherein the two sheets 1-1 are disposed with'their edges, which are to be joined together, in substantially abutting relation. Suflicient space, however, is left between such edges for the insertion therebetween of a thin strip or wire 2 preferably of the same metal as the sheets. Said strip 2 is shown as of rectangular form in order more closely to fit the space between the edges of sheet 1, but may be of circular or other cross-sectional form providing the mass of material in said strip is somewhat in excess of that required to fill the space in question. In other words, upon being melted down and interfused with the edges the resultant seam 3 should resemble that shown in Fig. 2.

The sheets 1 with strip 2 thus interposed between their edges are preferably supported on a plate 3 of copper or other heat conducting material, and in order to increase the cooling effect of the plate the latter may be made hollow as indicated, with suitable connections for circulating water through its interior.

The welding, as previously'indicated, is accomplished by means of an electric are, a carbon electrode 4 being employed, and the welding circuit including such carbon and either the plate 3 and strip 2 or such strip alone. It has been foundthat,'due .to the small amount of contact which the strip has with the plate, where the return circuit is through the latter, the circuit will be more or less diverted through the sheets 1 which have a much larger area of contact with the plate and thus the fusion of the strip will be retarded. However, by returning the current directly through the strip, as by means of a brush 5 moving in unison with the electrode (see Fig. 3), it is rendered impossible for the arc to be diverted to either of the sheets and it is caused to play directly on the strip. The latter is thus quickly melted down as the carbonpencil is drawn along it and the adjacent edges of the sheet 1 inter- 1 fused. forming a close and homogeneous joint that is smooth and continuous on both sides of the sheets.

The movement of the electrode, both longitudinally of the strip 2 and toward same, in 105 order to vary the character of the arc, may be effected by means of suitable mechanism, more or less automatic in character. Thus the control of the rate of feed of the carbon along the strip or seam may be made to 110 depend on the current fiow or amperage through the arc, while the vertical feed of the electrode, i. e., its movement towards the strip or seam, may be controlled by the voltage across the arc. The arrangement of wiring diagrammatically shown in Fig. 4 illustrates one way for thus automatlcally controlling the welding operation. The electrode 4, as well as the brush 5, which is 'here shown as forming the. connection for the return circuit direct with strip 2, both depend from a suitable slide or carriage 6 that is mounted so as to be movable longitudinally of the work in hne with the seam. For the purpose of thus feeding the slide 6 a screw 7 is provided, the same being-rotated by a motor 8 that has adjustable fields with the armature circuit across a resistance in series with the are, the fields being thus adjustable or variable so that the speed can be changed. For gradually lower ing the electrode 4 the stem 10 of the support for such electrode is vertically movable in slide 6, its movement being controlled by a nut 11 or equivalent device operated by a motor 12. A spring 13, in conjunction with the shoe 5 serves to hold the latter in contact with the strip 2, irrespective of the vertical position occupied by the electrode support. The motor 12, which is thus arranged to feed the electrode is of special construction, one field getting its exciting current as a shunt across the are, the other field being excited from'a constant source of voltage from some outside source, which can either be current from the exciter on'the welder, .or else current from some external direct current source. The two fields. under normal condi-' tions, will be equal and so no movement of the armature will occur with the current flowing through it; however, if the are becomes too long, the field excited across the arc will become stronger than the other field and the armature will turn in one direction, feeding the armature down. Conversely, when the arc becomes too short, the other field will become stronger than the field across the arc and will. cause the armature to revolve in the opposite direction until the arc was of the proper length. In this way the voltage across the arc will be maintained constant at all times.

From the foregoing arrangement of apparatus it will be seen that not only is the electrode advanced longitudinally of the strip at a greater or lower rate of speed, depending upon the volume of the current flow, as determined by the adjustment of resistance 9, but the lowering of the electrode automatically occurs as the end of the latter burns away, due to the change in voltage across the are.

In place of interposing a strip such as strip 2 between the meeting edges of the sheets to be melded, such edges may be brought directly into contact as shown in Fig. 4, and a strip corresponding with said strip 2 laid on top of the abutting edges. Such strip in.this case may be circular in cross section as shown, or rectangular, as in the-case of strip 2, and the latter may similarly be circular or any other desired shape. Furthermore, in place of the strip being entirely separate from the sheets, it may be formed as shown in Fig. 5 by turning up a portion of one of the sheets along the edge in question or, as shown in Fig. 6, the edges of both sheets may be thus, turned up.

The mode of operation and form of apparatus used, where the strip is formed and disposed as in these last mentioned figures, will remain the same as that previously described in connection with the arrangement wherein the strip is separate from, but clamped between, the juxtaposed edges of the sheets.

It will be understood that while referonce has hereinbefore been made to sheets 1 as though they were entirely independent of each other, they may consist simply of.

the opposite portions of a single sheet bent around into circular form so as to be brought intojuxtaposition, in the fashion desired. The term sheets is accordingly to he interpreted as including either two wholly independent sheets, or parts of a sheet thus bent around and brought into substantially the same plane. will, of necessity, be metal, such as iron or steel, capable of being worked electrically in the fashion described, and the strip, where separate from such sheets, may be of the same composition as the latter, or different as desired. Certain alloys of steel have amuch greater tensile strength and better characteristics otherwise than the ordinary mild steel so that by making the strip or filler rod,where it is to be placed between the two sheets or laid on top of the joint, of such special alloy steel a weld of superior character may be secured. For example, if a filler rod of Harveyized armor plate steel is used a very tough steel will result, the

The material of the sheets lUO tensile strength of which will exceed 100.000

pounds per square inch, while its ductility and toughness will be much greater than with the usual mild steel. By using filler rods of other alloys the character of the welding joint can be varied to suit special requirements. It will also be understood that the sheets as well as the strip, whatever the form of the latter, will be held in place by means of suitable clamps (not shown), pending the welding operation.

My improved process, in contra-distinction to that in which a metallic electrode is employed, produces a joint or weld that will bend much further without breaking, and is otherwise superior. This is due to the fact that with the metallic electrode method of welding each drop of metal cools by itself, and shrinkage stresses of Very considerable amount are accordingly set up in the weld; whereas with the carbon electrode method, as hereinbefore described, the whole weld is heated to the same temperature and cooled at the same time, so that no such shrinkage stresses are set up.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the method herein disclosed, provided the step or steps stated by any of the following claims or the e uivalent of such stated step or steps be em oyed.

I therefore particulary point out and distinctly claim as my invention 1. The method of welding together the edges ofmetal sheets, which consists in disposing such sheets with the edges to be welded in approximately abutting relation, providing an excess of metal adjacent such edges, and then melting such excess metal and interfusing the same with such edges by passing an electric arc longitudinally along such strip, the circuit connections being arrangedso as to concentrate the flow of curre nt in such excess metal.

2. The method of welding together the edges of metal sheets, which consists in disposing such sheets with the edges to be welded in approximately abutting relation, placing a strip of metal between such edges, and then melting such strip and interfusing same with such edges by passing an electric arc longitudinally along such strip, the circuit connections being arranged so as to concentrate the flow of current in such strip.

3. The method of welding together the edges of metal sheets, which consists in disposing such sheets with the edges to be welded in approximately abutting relation, placing a strip of metal between such edges, and then melting such strip and interfusing same with such edges by passing an electric are from a carbon electrode longitudinally along such strip, the circuit connections being arranged so as to concentrate the flow of cur rent in such strip.

4. The method of welding together the edges of metal sheets, which consists in disposing such sheets with the edges to be welded in approximately abutting relation, placing a strip of metal between such ed es, then melting such strip and interfusing same with such edges by passing an electric arc longitudinally along such strip, the circuit connections being arranged so as to concentrate the flow of current in such strip, and simultaneously cooling such sheets adjacent such edges.

5. The method of welding together the edges of metal sheets, which consists in placing a strip of metal between such edges, disposed in approximately abutting relation, and then melting such strip andinterfusing same with such edges by passing an electric are longitudinally along such strip, the return circuit being directly connected with such strip.

6. The method of welding together the edges of metal sheets, which consists in disppsing such sheets with the edges to be welded in approximately abutting relation, placing a strip of metal between such ed es, and then melting such strip and interfuslng same with such edges by passing an electric arc from a carbon electrode longitudinally along such strip, the return circuit being directly connected with such strip.

7. The method of Welding together the edges of metal sheets, which conslsts in sup-' porting the same on a heat conducting plate with such edges in approximately abutting relation, placinga metallic strip of substantially the same composition as that of such sheets between such edges, and then melting such strip and interfusing same with such edges by passing an electric arc longitudinally along such strip, the return circuit being directly connected with such strip.

8. The method of welding together the edges of iron or steel sheets, which consists in supporting the same on a copper plate with such edges-in approximately abutting relation, placlng a strip of ferrous metal between such edges, and then melting such strip and interfusing same with such edges by passing an electric arc longitudinally along such strip, the return circuit being directly connected with such strip.

Signed by me, this 21st day of February JAMES F. LINCOLN; 

